It is well known to provide a transverse scraper blade to engage the material carrying surface of the belt of an endless belt conveyor, with a view to scraping from that surface any material still adhering, following discharge of the material being conveyed from a discharge, or head, end of the conveyor. Conventionally, a scraper blade is located transversely of the conveyor belt, and of its direction of movement, at a zone where the belt begins its return run after passing over the head roller. Also conventionally, scraper blades are resiliently urged into contact with the belt surface by their support structure usually incorporating springs, so that the blade may deflect upon encountering a joint in the belt, which joint could be either a vulcanised joint or, more commonly, an array of metallic belt fastening hooks extending across the full width of the conveyor, which joint unavoidably constitutes a projection from the belt surface.
Whilst such a scraper blade is effective, to a greater or lesser extent, on a belt having a planar or relatively smooth, belt conveying surface, the material carrying surfaces of some belts are provided with an array of projections in the form of mounds, ribs etc., for better conveyance of material in circumstances where uphill, or a section of uphill conveying, is required, Such belts have always presented a scraping and cleaning problem and previous proposals have included rotary wire brushes and rollers with wrapper bars etc., in attempts to detach material adhering to the belt surface.
A basic object of the present invention is the provision of an improved conveyor belt scraper blade over previous proposals, particularly for use with belts having non-planar surfaces, and to a belt conveyor incorporating at least one such scrape blade.
According to a first aspect of the present invention, there is provided a scraper blade for a belt conveyor, comprising an elongate strip of synthetic plastics material, with an array of parallel cuts made into the strip from one lateral side towards the other lateral side, so as to define individual fingers between the cuts or kerfs, with the cuts extending to about half the width of the strip, so that the fingers are integral with the remaining, uncut portion of the strip, with one end of each finger adapted to engage the belt surface for scraping purposes and at the other end to be supported in suitable proximity to the belt surface to be scraped, with the individual fingers capable of deflection upon encountering any projection such as a mound or joint of the belt surface.
According to a second aspect of the invention there is provided a belt convevor incorporating at least one scraper blade in accordance with the first aspect.
Thus, the scraper blade in accordance with the invention deploys a non-unitary scraping edge comprising the array of fingers, with only the finger(s) that encounters a projection being deflected upon belt movement across the scraper, whereby unlike prior art proposals, the (unitary) blade is not lifted in its entirety from the belt surface, but only the finger(s) that needs to deflect is/are deflected, with the non-deflected fingers remaining in efficient scraping contact with the belt.
Preferably, the synthetic plastics material is polyurethane.
The fingers are rectangular in cross-section.
It is known that different grades, or mixtures, of polyurethane based materials may provide fingers of varying stiffness and resilience and hence varying performance characteristics, and clearly the grade selected should be that most suitable for the scraping task envisaged. It follows that, in producing a scraper blade, usually by pouring or casting flowable polyurethane into a mould, different grades may, be employed to provide different characteristics of stiffness for different parts of the blade.
A single, integral blade extends the full width of the belt involved.
A plurality of relatively short length blade modules are provided, e.g. four to eight, for a belt of one meter width, so that if, as expected, a blade has a propensity for wear in a particular area of the belt, it is only necessary to replace the worn module.